Hydraulic system for dies



May 17, 1966 F. M. WILLIAMSON HYDRAULIC SYSTEM FOR DIES Original Filed Dec. 51, 1959 INVENTOR. Flayd M Hz'ZZziw/safi United States Patent 3,251,214 HYDRAULMI SYSTEM FOR DIES Floyd M. Williamson, Detroit, Mich, assignor to Dr-Dro Engineering Company, Detroit, Mich, a corporation of Michigan Continuation of application Ser. No. 863,315, Dec. 31,

1959. This application Jan. 9, 1963, Ser. No. 250,444 5 Claims. (Cl. 72-351) This application is a continuation of my copending application Serial No. 863,315, now abandoned, and is a continuation-in-part of my copending patent application, Serial No. 768,889, now Patent No. 3,085,530 which latter application is a continuation-in-part of application Serial No. 455,270, now Patent No. 2,890,669.

This invention relates to hydraulic systems for dies and has particular reference to a press ram controlled hydraulic system for actuating dies for stripping and preforming operations.

The invention contemplates a hydraulic system where in a booster controlled by movement of the press ram is employed for substantially increasing the pressure of a low pressure hydraulic system for moving or controlling the movement of a die for stripping or preforming operations. The invention is particularly adapted to eflect a rapid stripping operation suitable for use in high speed presses. A hydraulic system incorporating the invention may also be employed to control the movement of a die for performing a preforming operation in such a press, and as a hydraulic cushion for resisting movement of a die upon closing of the press ram.

A principal object of the invention, therefore, is to provide a new, simple and efficient hydraulic system for use in connection with presses wherein the system is controlled by movement of the press ram for efiicientlyetiecting stripping and preforming operations on high speed presses.

Other and further objects of the invention will be apparent from the following description and claims and may be understood by reference to the accompanying drawing which by way of illustration shows a preferred embodiment of the invention and what I now consider to be the best mode of applying the principles thereof. Other embodiments of the invention may be used without departing from the scope of the present invention as set forth in the appended claims.

In the drawings:

FIG. 1 is a schematic view illustrating a hydraulicactuated stripper embodying the invention applied to a ram type press; and

FIG. 2 is an enlarged sectional View of the valve and booster unit.

As shown in FIG. 1, a shoe mounted on and .movable with the ram .of a ram type press is provided with a work cylinder 12 having a piston 14 reciprocable therein. A plurality of cylinders 12 and pistons may be provided. The end of the piston 14 reacts against the head 15 of a stripper pin or die member 16 which is reciprocable in a die 18 mounted on the shoe 10 and movable therewith. The ram is shown in its closed position in which the die 18 has cooperated with a die 20 fixed on the bolster of the press to form a blank 22 of sheet metal. Upon retraction of the ram, the piston 14 is advanced as here inatter explained so as to advance the pin 16 and strip the blank 22 from the die 18.

A tank 24 of hydraulic fluid under pressure, for example 80-100 lbs. per square inch, is connected by conduit 26 to a valve indicated generally at 23, and a con duit 30 interconnects the valve 28 and the cylinder 12 whereby fluid under the pressure to which it is subjected in the tank 24 is supplied from the tank to the cylinder 12 whereby the piston 14 and the die member 16 are nor- 3 ,251,214 Patented May 17, 1966 mally biased toward an extended position. On the closing of the press the engagement of the die member 16 with the blank 22 will eflect the retraction of the die member 16 and the piston 14, and displace fluid from the cylinder 12 through the conduit 30 and the valve 28 and the conduit 26 back to the tank 24. However, upon the upstroke of the press, the booster indicated generally at 29 will be effective to supply hydraulic fluid at a pressure substantially higher (5 to 10 times) than that in the tank 24 to the conduit 30 and the cylinder 12 for advancing the piston 14 and the die member 16 to their extended position to effect the rapid stripping of the formed blank 22 from the die 18.

The valve 28 includes a bore 32 to the threaded end of which the conduit 26 is connected in fluid flow relation by a threaded coupling member (not shown). A passage 34 communicates at one end with the bore 32 and at its other end with a check valve chamber 36 in which a spring pressed check valve 38 is disposed. A bushing 40 forming one end of the passage 34 forms a seat for the ball valve 38 whereby hydraulic fluid may flow from the passage 34 into the valve chamber 36 but not in a reverse direction. The valve chamber 36 communicates with a cross passage 42 which intersects passage 44 and the end of which passage 42 is closed by a plug 46. The lower end of passage 44 communicates with the hydraulic cylinder of booster 29;. A piston 52 reciprocable in the cylinder 50 is connected to an air piston 54 which is reciprocable in air cylinder 56. The upper end of the passage 44 communicates with the space inside of a cylindrical valve sleeve is disposed in a cylindrical valve chamber 62 in valve 28. A cup-shaped cylindrical valve member 64 reciprocable in the valve sleeve 60 is biased to its seat 66 around the end of the passage 44 by spring 68. The end of the conduit 30 is connected by means of a threaded coupling (notshown) in fluid flow relation to the port 70 which communicates with the valve chamber 62. The spring 68 is seated against an apertured disc 72, the aperture of which communicates through opening 74 with the bore 32.

Thus with the parts in the position shown in FIG. 2,

fluid is free to flow under the pressure in the tank 24 from the bore 32 to the port '76 through the passage '74, the aperture in the disc 72, the sleeve 60, and the radially extending openings 76 in the sleeve 60 which provide communication between the interior of the sleeve and the space between the exterior of the sleeve 60 and the inside of the valve chamber 62 with Whichthe port 70 communicates. The resistance offered by the spring 37 which seats the ball valve 38 is very slight so that fluid is also free to flow under the pressure in the: tank 24 from the bore 32 through the passage 34 into the valve chamber 36, through the passage 42 into the passage 44, and thence into the hydraulic cylinder 50 of the booster 29 for the purpose of charging cylinder 50 and retracting the piston 52, assuming that the air cylinder 56 of the booster is ported to atmosphere at such time.

In the position in which the parts are shown in FIG. 1, the closing of the press has moved the piston 14 to its retracted position which efi'ects the flow of hydraulic fluid from the cylinder 12 through the conduit 30, the port 70, the openings 76 in the sleeve 60, the apertures in the disc 72, the passage 74, the bore 32, and the conduit 26. Upon retraction of the press ram, the blank 22 will tend to move with the die 18. Upon energization of the booster 29 the piston 52 thereof will eifect the discharge of hydraulic fluid from the hydraulic booster cylinder 50 to the cylinder 12 for actuating the piston 14 to move the pin 16 for stripping the blank 22 from the die 18.

The air pressure supplied to the air cylinder 56 may be connected to the same source of air pressure to which the tank 24 is connected. The advancing of the air piston 54 will subject the hydraulic fluid in the cylinder 50 to a pressure many times in excess of the pressure in the tank 24, say 5 to times, and will discharge such hydraulic fluid through the passage 4-4. This will unseat the valve member 64 and more it upwardly so as to expose the openings 80 whereby the hydraulic fluid under the pressure to which it is subjected by the booster 29 will be forced through the openings 80 and the port 70 and the conduit 30 to the work cylinder 12. The valve 38, of course, is seated at such time and will prevent the return flow of oil from the passage 42 into the passage 34. The valve 64 in response to the discharge of fluid from cylinder 50 is moved upwardly within the sleeve 60 so as to seat on disc 72 and close the openings 76 and thereby close the fluid connection between the tank 24 and the cylinder 12 and prevent the flow to the tank 24 of the fluid discharged from cylinder 50. The hydraulic fluid under pressure supplied to the cylinder 12 due to such energization of the booster will advance the piston 14 and the die member 16 and strip the blank 22 from the die 18.

When the air pressure in the cylinder 56 is released, hydraulic fluid under the pressure to which it is subjected in the tank will retract the piston 52 of the hydraulic booster cylinder 50. To relieve excess pressure which may develop in conduit 30 when valve 64 is seated on disc '72, a pressure relief by-pass is provided and comprises a cylindrical valve chamber 82 which intersects the passage 34 and in which a cylindrical sleeve valve member 84 is arranged, A passage 86 extending between the valve chamber 82 and the cylindrical valve chamber 62 communicates with the space within the sleeve 84. A cupshaped cylindrical valve member 88 is reciprocable within the sleeve 84 and is biased against the seat 90 by a spring 92 which seats against an apertured valve disc 94. The sleeve 84 is provided with radially extending openings 96 which communicate with the space within the valve chamber 82 exteriorly of the sleeve 84. A restricted opening 98 is provided in the valve member 88 so as to permit the flow of oil from the passage 86 through the opening 98 into the interior of the sleeve 84. i

The valve disc 94 provides an annular valve seat 1% around the aperture in the disc 94 and a conical valve member 102 is seated on such seat by a spring 1% backed up by cap 106. The space around the conical valve member 102 communicates via passage 108 with bore 32. The relief valve construction just described provides a pressure relief valve between conduits 26 and 3d, and the valve construction just described is basically that disclosed in my prior patent No. 2,901,238, issued August 25, 1959, for Circulating System for Hydraulic Liquid Between Tanks and Cylinders.

When the valve 64 is seated on the disc 72 due to the discharge of fluid from the booster cylinder 51), the pressure in the conduit 30 will be substantially higher than the pressure in the conduit or line 26, and the high pressure thus transmitted to the cylinder 12 will be effective to advance the piston 14 and the die member 16. The pressure relief valve 88, 94, 102 permits the dissipation of excess pressure in the line 31). The pressure at which the relief valve opens depends upon the pressure applied to the valve member 102 by the spring 104, and this pressure may be adjusted by changing the position of the cap 106. Normally the pressure relief valve is set to release pressure in the system at a pressure higher than that devel oped in the system by the energization of the booster 29.

Air is supplied to the booster cylinder 56 through an air pressure line 110 having an air cycling valve 112 arranged therein, and a conduit 114 interconnects the valve 112 and the booster cylinder 56. Normally the valve 112 is set so that the cylinder 5d is ported to atmosphere, thus permitting the normal pressure on the fluid in the tank 24 reacting on the piston 52 of the booster 29 to retract the piston 52 and thereby recharge the cylinder 59. An adjustable cam 116 movable with the press ram is engageable with an arm 118 of a limit switch 120 which actuates the valve 112. Thus on the upstroke of the press ram, the cam 116 will momentarily engage the arm 118 and close the switch so as to actuate the valve 112 to connect air under pressure to the conduit D14 and to shut off the atmosphere vent, thereby energizing the booster 29 and advancing the piston 54 and the air cylinder 56 so that the hydraulic piston 52 will discharge fluid from the booster cylinder 50 through the passage 44 as previously described into the line 30 leading to the cylinder 12. The cam 116 will engage the switch arm 118 for a length of time so that the valve 112 will be open for a sufficient length of time to eifect the power stroke of the piston 54. After the cam 116 passes out of contact with the arm 118, it will return to its normal position and open the switch 120 so as to permit the valve 112 to shut off the air pressure supply to the cylinder 56 and to port the same to atmosphere.

Where it is desired to employ the system to effect a preforming operation wherein a die member such as 16 projects below the die 18, the cam 116 will be set so as to trip the arm 118 on the closing of the press so that high pressure will be supplied to the hydraulic system due to the energization of the booster 29 prior to the closing of the press. The high pressure thus supplied to the cylinder 12 will maintain the preforming die in its advanced position to effect the preforming operation. Upon the closing of the press, the excess pressure developed in the system in the line 30 will be dissipated through the pressure relief valve previously referred to. The cam may also be set so as to trip the arm 118 during opening of the press as well as during closing of the press so as to provide high pressure for stripping as well as for preforming and preloading. A pressure regulating valve 124 in the air pressure supply line to the tank 24 serves to regulate and maintain the pressure in the latter at whatever level is desired. The hydraulic system disclosed isextrernely flexible because of the valve 28 and because the booster 29 can be energized at different parts of the press cycle or more than once during each cycle of press operation for moving or controlling movement of the die or stripping or preforming operations.

While I have illustrated and described a preferred i embodiment of my invention, it is understood that this is capable of modification, and I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. In combination a ram type press, a work cylinder, a piston reciprocable in said cylinder, said cylinder and piston being arranged relative to the press ram so that closing of the press ram retracts said piston, a die member connected to said piston so as to move therewith, a tank of hydraulic fluid under pressure, a normally open first fluid connection between said tank and cylinder through which hydraulic fluid under pressure is supplied from said tank to said cylinder, an air pressure operated booster including a booster hydraulic cylinder, a second fluid connection between said tank and booster hydraulic cylinder through which hydraulic fluid under pressure is supplied from said tank to said booster hydraulic cylinder, a normally closed check valve in said second connection which permits fluid flow therethrough in a direction from said tank to said booster hydraulic cylinder, a third fluid connection between said booster hydraulic cylinder and said work cylider through which hydraulic fluid is supplied from said booster hydraulic cylinder to said work cylinder, a valve in said first and third fluid connectionswhich is normally positioned so that said first connection is open and which is responsive to the discharge of fluid from said booster hydraulic cylinder to close said first connection and to permit fluid flow from said booster hydraulic cylinder through said third connection to said work cylinder, a by-pass between said work cylinder and sand tank and around said valve when the latter is positioned to close said first fluid connection, a pressures relief valve in said by-pass, and means controlled by movement of said press ram for supplying airv under pressure to said booster to effect the discharge of hydraulic fluid from said booster hydraulic cylinder through said third fluid connection to said work cylinder thereby toetfect movement of said piston to an extended postion relative to said ram.

2. In combination a ram type press, a hydraulic work cylinder, a piston reciprocable in said cylinder, said cylinder and piston being arranged relative to the press ram so that closing of the press raim retracts said piston, a die member connected to said piston so as to move therewith, a tank of hydraulic fluid under pressure, a first fluid connection between said tank and cylinder through which hydraulic fluid under pressure is supplied from said tank to said cylinder, a booster hydraulic cylinder, a second one-way fluid flow connection between said tank and booster hydraulic cylinder through which hydraulic fluid under pressure is supplied from said tank to said booster hydraulic cylinder, a third one-way fluid flow connection between said booster hydraulic cylinder and said work cylinder through which hydraulic fluid under the discharge pressure of the booster hydraulic cylinder is supplied from said booster hydraulic cylinder to said work cylinder, a normally open valve in the first connection movable to a position to close such connection in response to the discharge of fluid .from said booster hydraulic cylinder, a by-pass between said work cylinder and said tank and around saidvalve in said first fluid connection, a pressure relief valve in said bypass, and means actuated by said press ram for energizing said booster hydraulic cylinder to effect the discharge of hydraulic fluid from said booster hydraulic cylinder through said third fluid connection to said work cylinder to move said piston and die member to an extended position relative to said ram.

3. In combination a ram type press, a hydraulic work cylinder, a piston reciprocable in said cylinder, said cylinder and piston being arranged relative to the press ram so that closing of the press ram retracts said piston, a die member arranged to be moved by said piston, a tank of hydraulic fluid under pressure, a first fluid connection between said tank and cylinder through which hydraulic fluid under pressure is supplied from said tank to said cylinder, a booster hydraulic cylinder, a second fluid connection between said tank and booster hydraulic cylinder through which hydraulic fluid under pressure is supplied from said tank to said booster hydraulic cylinder, a third fluid connection between said booster hydraulic cylinder and said work cylinder through which hydraulic fluid under the discharge pressure of said booster hydraulic cylinder is supplied from said booster hydraulic cylinder to said Work cylinder, a valve in the first connection movable in response to the discharge of fluid from said booster hydraulic cylinder to prevent the flow of fluid in said first connection in a direction from said work cylinder to said tank, a by-pass around said valve, a pressure relief valve in said by-pass, and means actuated by said press ram for energizing said booster hydraulic cylinder to effect the discharge of hydraulic fluid from said booster hydraulic cylinder through said third fluid connection to said Work cylinder to move said piston and die member to an extended position relative to said ram.

4. In combination a ram type press, a work cylinder, a piston reciprocable in said cylinder, said cylinder and piston being arranged relative to the press ram so that closing of the press ram retracts said piston, a die member connected to said piston so as to move therewith, a tank of hydraulic fluid under pressure, a first fluid connection between said tank and cylinder through which hydraulic fluid under pressure is supplied from said tank to said cylinder, a booster including a booster hydraulic cylinder, a second one-way fluid flow connection between said tank and booster hydraulic cylinder through which hydraulic fluidunder pressure is supplied to said booster hydraulic cylinder, 21 third fluid connection between said booster hydraulic cylinder and said work cylinder through which hydraulic fluid is suppliedfrom said booster hydraulic cylinder to said work cylinder, a valve means in said first and third fluid connections which permits fluid flow from said booster hydraulic cylinder to said work cylinder and prevents hydraulic fluid discharged by said booster hydraulic cylinder from returning through said first connection to said tank, a bypass between said work'cylinder and said tank and around said valve means, a pressure relief valve in said by-pass, and means actuated by said press ram for energizing said booster to effect the discharge of hydraulic fluid from said booster hydraulic cylinder through said third fluid connection to said work cylinder to move said piston to an extended position relative to said ram.

5. In a press, a hydraulic system for controlling the dies thereof comprising a hydraulic circuit including an actuating cylinder with a piston actuated by hydraulic fluid pressure, a die associated with said piston so as to retract said piston upon closing of the press, a low pressure supply tank with hydraulic fluid under low pressure, a high pressure cylinder, a valve with a bore therein, ports in said bore leading to the high pressure cylinder, the actuating cylinder and the supply tank whereby said cylinders are supplied with hydraulic fluid under tank pressure, a spool in said bore, a spring biasing said spool so as to block the flow between two of said ports, said spool moving in response to the discharge of hydraulic fluid from the high pressure cylinder when cycled in one direction to direct said high pressure fluid to the actuating cylinder and being moved by the spring when the cylinder is reversed to direct the fluid from the actuating cylinder back to the low pressure supply tank, means for cycling said high pressure cylinder, said spool being biased by said spring so that the valve ports leading to said tank and actuating cylinder are open when the high pressure cylinder is deenergized so as to provide open two-way fluid flow communication between said tank and actuating cylinder and a pressure relief bypass connected around said valve set to open at a higher pressure than the discharge pressure of said high pressure cylinder.

References Qited by the Examiner UNITED STATES PATENTS 2,303,628 12/ 1942 Geiger et a1. 113-5O 2,305,610 12/ 1942 Ernst 1l3-50 2,890,669 6/1959 Williamson 113-46 2,918,272 12/ 1959 Williamson 113--46 3,085,530 4/1963 Williamson 1l3-46 CHARLES W. LANHAM, Primary Examiner. 

1. IN COMBINATION A RAM TYPE PRESS, A WORK CYLINDER, A PISTON RECIPROCABLE IN SAID CYLINDER, SAID CYLINDER AND PISTON BEING ARRANGED RELATIVE TO THE PRESS RAM SO THAT CLOSING OF THE PRESS RAM RETRACTS SAID PISTON, A DIE MEMBER CONNECTED TO SAID PISTON SO AS TO MOVE THEREWITH, A TANK OF HYDRAULIC FLUID UNDER PRESSURE, A NORMALLY OPEN FIRST FLUID CONNECTION BETWEEN SAIDTANK AND CYLINDER THROUGH WHICH HYDRAULIC FLUID UNDER PRESSURE IS SUPPLIED FROM SAID TANK TO SAID CYLINDER, AN AIR PRESSURE OPERATED BOOSTER INCLUDING A BOOSTER HYDRAULIC CYLINDER, A SECOND FLUID CONNECTION BETWEEN SAID TANK AND BOOSTER HYDRAULIC CYLINDER THROUGH WHICH HYDRAULIC FLUID UNDER PRESSURE IS SUPPLIED FROM SAID TANK TO SAID BOOSTER HYDRAULIC CYLINDER, A NORMALLY CLOSED CHECK VALVE IN SAID SECOND CONNECTION WHICH PERMITS FLUID FLOW THERETHROUGH IN A DIRECTION FROM SAID TANK TO SAID BOOSTER HYDRAULIC CYLINDER, A THIRD FLUID CONNECTION BETWEEN SAID BOOSTER HYDRAULIC CYLINDER AND SAID WORK CYLINDER THROUGH WHICH HYDRAULIC FLUID IS SUPPLIED FROM SAID BOOSTER HYDRAULIC CYLINDER TO SAID WORK CYLINDER, A VALVE IN SAIDFIRST AND THIRD FLUID 